Pollen morphology of the genus Phyllanthus (Euphorbiaceae) W. Punt Botanical Museum and Herbarium, State University, Utrecht (The Netherlands) (Received September 3, 1966) (Revised November 24, 1966) SUMMARY Some pollen types occurring in the genus Phyllanthus are arranged into two series morphological series. These are based on seven “evolutionary trends”. INTRODUCTION is the and most diversified the in the Phyllanthus largest genus among genera subfamily Phyllanthoideae of the Euphorbiaceae. Webster(1956-1958), at present undertaking a revision of Phyllanthus, estimates the total number of species at 650 and Léandri (1958), in Paris, suggested a probable total of 1,700 species. The includes of from such genus a great many types growth as trees, shrubs, annuals and perennial herbs. The distribution of the genus is circumtropical and well represented on all continents and particularly on the off-shore island groups and Caledonia. The classification of such as Cuba, Madagascar New present reflects the true between the Phyllanthus very inadequately relationships subgeneric taxa (Webster, 1956). current not Phyllanthus in its circumscription is entirely a natural genus. There differences in the flowers and fruits. It is are profound vegetative structure, not surprising that the pollen grains in this genus also show an extraordinary diversity of pollen types. In this short report the author will try to give a brief their outline of some pollen types and mutual relationships. The diversity, however, is so large, that such an outline can only be considered incomplete. METHODS AND TERMINOLOGY The pollen grains studied were treated according to the acetolysis method described by Erdtman in 1943 and revised by him in 1960. The grains have been Rev. Palaeobotan. Palynol., 3 (1967) 141-150 141 embedded in glycerine-jelly. The microphotographs were taken with a Leitz Ortholux microscope, combined with a Leitz Orthomat camera. used in this is The terminology paper partly after Erdtman(1952) and partly after Punt (1962). TAXONOMICAL AND PHYLOGENETICAL RELATIONSHIPS If it is accepted that evolution actually took place, this evolution must be much data supported by as as possible, e.g., palaeobotanical, phytogeographical, cytotaxonomical and other taxonomicaldata. It is a pity that solittlepalaeobotanical informationis known from Euphorbiaceae-Phyllanthoideae and this is one more reason for accumulating as much recent data as possible before discussing the probable phylogenetical relationships. Webster(1956-1958) has already accumulat- ed much phytomorphological, cytotaxonomical (Webster and Ellis, 1962) and other taxonomical data. According to these data some species were considered primitive and others appeared to be advanced. The author felt that pollen morphology might give additional support for the position of Websters primitive and advanced taxa. If, moreover, pollen mor- and would arrive the phology taxonomy at same conclusion, this would mean a real advance in the subdivision of the genus. One of the suggestions which Webster made is that there is a relationship the between Phyllanthus and presumably primitive genera Securinega, Andrachne and of the If that of Savia same family (Webster, 1956). we assume, some species which show with the Andrachne and Phyllanthus relationships genera Securinega, Savia are the most primitive ones in this genus, than it seems logical to accept, that of exhibit the characteristics which the pollen grains these taxa are also primitive. Pollen grains of several species of Phyllanthus (P. hamiltonianus, P. kirkianus, P. maderaspatensis and P. profusus) indeed resemble those of Securinega, Andrachne and Savia (Webster, 1956; Punt, 1962; Köhler, 1965). These species are tricolpor- and have ate, distinctly prolate, reticulate an elongated endoaperture (Plate IA-D). One thing should be kept in mind, viz. that so-called “primitive” pollen grains of the genus Phyllanthus are already “advanced” in comparison to the other pollen types in the Plant Kingdom, e.g., monoaperturate and 3-colpate grains in Magnoliaceae and Ranunculaceae (Erdtman, 1952). If of and allies the we accept pollen grains P. maderaspatensis its as being most in the then the characters primitive genusPhyllanthus, pollen-morphological in other pollen grains are advanced. The evolution of the pollen characters is demonstratedby means of successions which the author calls “evolutionary trends” (Fig.l). In studying the pollen grains of Phyllanthus several of these trends could be distinguished and the most important ones are shown in Table I. There is not a at special sequence in which the evolutionary trends occur. All trends may occur series of any point in any pollen types. 142 Rev. Palaeobotan. PalynoL, 3 (1967) 141-150 PLATE I (p.144) All magnifications are X2,000. A. Andrachne phyllanthoides. B. Securinega peltandra. C. Securinega microcarpa; reticulum. D. Phyllanthus maderaspatensis. El. P. acidus; endoporus. E2. P. acidus; colpi anastomosing at the pole. F1. P. pynaertii; colpi not anastomosing at the pole. F2. P. pynaertii; polar view. G. P. glaucus; polar view, anastomosing colpi. PLATE II (p.145) All magnifications are x2,000. Al. P. casticum; polar view, colpi anastomosing. A2. P. casticum; equatorial view, endoporus. B1. P. cryptophilus; reticulum at high focus. B2. P. cryptophilus; reticulum at low focus, colpus borders at high focus. B3. P. cryptophilus; double endoporus. B4. P. in double visible in cryptophilus;single porus focus, porus faintly right-hand colpus. C1. P. warburgii; equatorial view; endoporus. C2. P. warburgii; polar view, colpi at high focus. C3. P. warburgii; colpi at low focus. D1. P. miquelianus; colpi and endopori in focus. D2. P. miquelianus; same grain in optical section. E. P. welwitschianus; endopori. PLATE III (p.146) All magnifications are x2,000. Al. reticulum and P. welwitschianus: one porus. A2. P. welwitschianus; five colpi. B1. P. Websterianus; reticulum. B2. P. websterianus; double porus. C1. P. fasciculatus; optical section. C2. P. fasciculatus; reticulum. PLATE IV (p.147) Al. P. emblica; polar view, optical section; magnification X2,000. A2. P. emblica; equatorial view, optical section; magnification x 2,000. A3. P. emblica; colpus and endoporus; magnification x2,000. A4. P. emblica; reticulum; magnification x2,000. B1. P. ruscifolius; equatorialview, optical section; magnification x 1,300. B2. P. ruscifolius; equatorial view, optical section; magnification x2,000. B3. P. ruscifolius; colpus and endoporus; magnification x 2,000. Rev. Palaeobotan. Palynol., 3 (1967) 141-150 143 PLATE I 144\I Rev. Palaeobotan. Palynol., 3 (1967) 141-150 PLATE II Rev. Palaeobolan. Palynol., 3 (1967) 141-150 145\II PLATE III 146\III Rev. Palaeobotan. Palynol., 3 (1967) 141-150 PLATE IV Rev. Palaeobotan.Palynol., 3 (1967) 141-150 147\IV Fig.1. Evolutionary trends. In this paper two series of pollen types are shown (Table I and II). The series may be of evolutionary value, but because additional palaeobotanical, cytotaxonomical and other morphological evidence for the supposed evolution available this it consider series is not yet at moment, seems better to these for the time being as morphological series only. CONCLUDING REMARKS In additionto the two series shown in TableI and II, it is possible to arrange some more series, taking the P. maderaspatensis type as starting point. Space is too it limited, however, to show all morphological series. Moreover, was impossible to 148 Rev. Palaeobotan. Palynol., 3 (1967) 141-150 CC3)3) 2, C 2)2) 1, F C 1, H SMITHSMITH FF ARG. I (Plate J.J. Plate(Plate BAILL. GAGEGAGE PAX MUELL.. HLD.( SCHUM. itifoilus bmnus WILD. us us neus ovatifoilus papuanus; aeaeneus ovt pa DeDel K.K. polyantlpolyanthus purpureus P. P. P. P.purpure e.g., pynaertii P. P. warburgii P.P. p.P. 2) 7 n D 1 1, 2) 2)2) D E EXELL HO H A 1, G) ARG.ARG. 1, D) I D) E A (Plate I I ARG. KUNTZE) HII (Plate ARG. SMITH ARG. ARG.ARG. (Plate MUELL.MUELL. BROWN (Plate (Plate (O. MORONG J. *— POIR. POIR. L. J.J. HUTCH. ARG. POIR. MERR.MERR. MAXIM. MUELL. J. MUELL. BEILLE N.E. BAILL. MUELL. MUEL. FOST.POST. SKEELS URB. WILLEM.WILLEM. hamiltonianus muellerianus MUELL. g&no (L.) chacoensis maritimus r. _ kirkianus profusus elsiae delpyanusdelpyanus flexuosusreticulatusreticulatus multiflorus vergens alpestris griffithii pamyensispanayensis usuriensisusuriensis virgatus P.flexuosus t/c naderaspatensis , maderaspatensis P. P.P. P. P. P.P. P. P. P.P. ’.iquelianus asticum P. P. P. P. P.P. P.P. P. P. P. cidus laucus P. jr a miquelianus j [ casticum glaucus I acidus |5 Ö t I13i 2A < g1 2 r, P.P. P. P. P. P. Fig.l (cf. ' _ •6a ARG. _ trends 4) ARG. MUELL. B 2) 3 ARG.ARG. 3, A WEBSTER B indicate 1, 1, 2)2) 1 2, I A JUSS.) MUELL. C B IIIHI 1, MUELL. 1, SERIES (A. C numbers E, B HI schianus IIn ulatus HI ceramanthus Hn ate B ate with i I ” 2[BJ (Plate 2 (Plate (Plate welwitschianus (PI (PI P. welivi fascicfasciculatus cryptophilus TABLE MORPHOLOGICAL P. Arrows P. P. P. 1 Rev. Palaeobotan. Palynol., 3 (1967) 141-150 149 TABLE II II MORPHOLOGICAL SERIES 1 P. maderaspatensis L.L. (Plates(Plates I D) yu P. emblica L. (Plate IV A 1, A 2, A 3, A 4)4) P. gunnii J.D. HOOK. "I3i P. P. ruscifolius MUELL. ARG. (Plate IV B 1, B 2, B 3) ele Ti P. websterianus STEYERMARK (Plate HI B 1, B 2) 1 Arrows with numbers indicate trends (cf. Fig.l). additional give any information on the taxonomical results in this subject. In collaborationwith Professor G. L. Webster, the author is preparing a more detailed classification of the genus Phyllanthus based on both pollen morphology and tax- onomy. ACKNOWLEDGEMENTS The present study was done in close cooperation with Professor G. L. Web- ster, Davis, Calif., U.S.A. Without his kind help, ample advise and critical comment would have been it impossible for the author to communicate the present data. REFERENCES Erdtman,G., 1943. An Introduction to Pollen Analysis.